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The 12 BaZi Birth Hours Table & Why 11:00–11:59 PM Produces Different Pillars

Last updated: October 22, 2026

Traditional Four Pillars (BaZi) divides the 24-hour solar day into twelve two-hour branches (shichen), named after the twelve Earthly Branches from Zi (Rat) through Hai (Pig), measured by the birthplace's local True Solar Time.12

Because the Zi (Rat) Hour (23:00–00:59) straddles midnight, births between 23:00 and 23:59 (11:00–11:59 PM local solar time) can be cast under two different classical conventions: switching the Day Pillar at 23:00 (whole Zi hour) or splitting the hour at 00:00 midnight into Late Zi (23:00–23:59, keeping the current day's Day Pillar) and Early Zi (00:00–00:59, taking the next day's Day Pillar).2 Xiaodao includes an "Early/late Zi" setting (defaulting to "No", the 23:00 switch) and pops up a choice whenever a birth time falls near a branch or day boundary so you can confirm which side of the boundary to cast.3

Full Reference Table: The 12 Two-Hour Branches (Shichen)

In BaZi, each two-hour solar window sets the Earthly Branch of the Hour Pillar; the Heavenly Stem of the Hour Pillar is derived using the classical five-elements hour cycle (Wu Shu Dun). All time windows below refer to local True Solar Time at the birthplace (after adjusting for Daylight Saving Time and longitude):12

OrderEarthly Branch (Shichen)Animal SymbolLocal True Solar Time WindowElement & PolarityNotes on Boundaries
1Zi (子)Rat23:00 – 00:59 (11:00 PM – 12:59 AM)Yang WaterStraddles midnight; 23:00–23:59 differs between the 23:00 day-switch and Early/Late Zi conventions
2Chou (丑)Ox01:00 – 02:59 (1:00 AM – 2:59 AM)Yin EarthEarly morning; 01:00 marks the Zi–Chou transition
3Yin (寅)Tiger03:00 – 04:59 (3:00 AM – 4:59 AM)Yang WoodPre-dawn hours
4Mao (卯)Rabbit05:00 – 06:59 (5:00 AM – 6:59 AM)Yin WoodSunrise window (06:00 equinox solar sunrise)
5Chen (辰)Dragon07:00 – 08:59 (7:00 AM – 8:59 AM)Yang EarthMorning hours
6Si (巳)Snake09:00 – 10:59 (9:00 AM – 10:59 AM)Yin FireLate morning
7Wu (午)Horse11:00 – 12:59 (11:00 AM – 12:59 PM)Yang FireSolar noon window (12:00 is local solar noon when the Sun crosses the meridian)
8Wei (未)Goat / Sheep13:00 – 14:59 (1:00 PM – 2:59 PM)Yin EarthEarly afternoon
9Shen (申)Monkey15:00 – 16:59 (3:00 PM – 4:59 PM)Yang MetalMid-to-late afternoon
10You (酉)Rooster17:00 – 18:59 (5:00 PM – 6:59 PM)Yin MetalSunset window
11Xu (戌)Dog19:00 – 20:59 (7:00 PM – 8:59 PM)Yang EarthDusk and evening
12Hai (亥)Pig21:00 – 22:59 (9:00 PM – 10:59 PM)Yin WaterLate evening; 23:00 marks the start of the Zi hour

Why Two Calculators Can Disagree on an 11:30 PM Birth: Whole Zi vs. Early/Late Zi

In pre-modern China, the Zi double-hour began at 23:00 (Zi Chu). When modern civil calendars fixed the date change at 00:00 midnight (Zi Zheng), two schools of practice emerged for births occurring between 23:00 and 23:59 local True Solar Time:2

FeatureConvention A: Whole Zi / 23:00 Day ChangeConvention B: Split Early/Late Zi / 00:00 Midnight Day Change
Xiaodao "Early/late Zi" Setting"No" (Default)"Yes" (Page helper note: non-specialists don't need to touch this; the default is fine)
When the Day Pillar ChangesAt 23:00 local True Solar TimeAt 00:00 midnight local True Solar Time
Day & Hour Pillars for a 23:00–23:59 BirthFrom 23:00 onward, the Day Pillar is the next day's pillar, and the Hour Stem is derived from the next day's Day StemCounts as Late Zi (Night Zi, 晚子时 / 夜子时): the Day Pillar remains the current day's pillar, while the Hour Stem borrows the next day's Day Stem (e.g., on a Jia day, Late Zi is Bing-Zi)
Day & Hour Pillars for a 00:00–00:59 BirthCasts the Day Pillar for the birth date (the new day), with the Zi Hour PillarCasts the Day Pillar for the birth date (the new day), and the Hour Pillar is Early Zi (早子时)

For example, if Day 1 is Jia-Zi and Day 2 is Yi-Chou, a birth at 23:30 local solar time on Day 1 receives the Yi-Chou Day Pillar (Yi Wood Day Master) and Bing-Zi Hour Pillar under Convention A, whereas under Convention B (Late Zi) it retains the Jia-Zi Day Pillar (Jia Wood Day Master) while borrowing the next day's Yi stem to form the Bing-Zi Hour Pillar. For a birth between 00:00 and 00:59, both conventions cast the Day Pillar for the birth date (the new day) with the Early Zi Hour Pillar.

General-purpose chat models that cast BaZi charts without asking or disclosing their Zi-hour rule often default silently to 00:00 civil midnight or 23:00 clock time without converting to True Solar Time first; we recommend checking any late-night birth with a calculator that displays both True Solar Time and the active Zi convention.

How to Check a Late-Night or Odd-Hour Birth on Xiaodao

  1. Check True Solar Time first: A clock birth at 11:20 PM (23:20) during summer Daylight Saving Time or in a city west of its time zone's meridian often converts to 10:15 PM (22:15, the Hai Hour) in local True Solar Time—meaning it does not fall in the Zi hour at all.
  2. Choose your "Early/late Zi" preference if needed: In Xiaodao's BaZi Calculator, "Early/late Zi" defaults to "No" (23:00 day switch). If you follow the split Zi tradition, switch "Early/late Zi" to "Yes".
  3. Use the boundary prompt: When a birth time lands close to a two-hour branch boundary or day boundary, the page pops up a choice so you can confirm which side of the boundary to cast.3

Frequently Asked Questions

No. Once local True Solar Time passes 00:00 midnight (00:00–00:59), both conventions cast the Day Pillar for the birth date (the new day), with the Zi (Early Zi) Hour Pillar. The difference applies only when local True Solar Time falls between 23:00 and 23:59.

Born Near 11 PM or an Odd-Hour Boundary? Check Your Pillars

Enter your birth date, local clock time, and birthplace in Xiaodao's free BaZi Calculator to check local True Solar Time, toggle "Early/late Zi" if needed, and confirm boundary choices. Visitors can preview the four natal pillars and header details without signing in; signing up and saving a profile unlocks the Luck Pillars, annual, and monthly Timeline. First-time registration grants 200 Dao Points immediately upon sign-up.

Cast a Bazi chartSample report

Sources

  1. 1

    Hong Kong Observatory, Heavenly Stems and Earthly Branches. The twelve Earthly Branches and two-hour shichen periods.

  2. 2

    Wan Minying, San Ming Tong Hui, volume 2, “论四时节气,” “论遁月时,” and “论年月日时.” Classical branch hours and Hour Stem derivation.

  3. 3

    Xiaodao, public FAQ (https://xiaodaox.com/en/guide/faq), checked October 22, 2026.

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The 12 BaZi Birth Hours Table & Why 11:00–11:59 PM Produces Different Pillars

Last updated: October 22, 2026

Traditional Four Pillars (BaZi) divides the 24-hour solar day into twelve two-hour branches (shichen), named after the twelve Earthly Branches from Zi (Rat) through Hai (Pig), measured by the birthplace's local True Solar Time.12

Because the Zi (Rat) Hour (23:00–00:59) straddles midnight, births between 23:00 and 23:59 (11:00–11:59 PM local solar time) can be cast under two different classical conventions: switching the Day Pillar at 23:00 (whole Zi hour) or splitting the hour at 00:00 midnight into Late Zi (23:00–23:59, keeping the current day's Day Pillar) and Early Zi (00:00–00:59, taking the next day's Day Pillar).2 Xiaodao includes an "Early/late Zi" setting (defaulting to "No", the 23:00 switch) and pops up a choice whenever a birth time falls near a branch or day boundary so you can confirm which side of the boundary to cast.3

Full Reference Table: The 12 Two-Hour Branches (Shichen)

In BaZi, each two-hour solar window sets the Earthly Branch of the Hour Pillar; the Heavenly Stem of the Hour Pillar is derived using the classical five-elements hour cycle (Wu Shu Dun). All time windows below refer to local True Solar Time at the birthplace (after adjusting for Daylight Saving Time and longitude):12

OrderEarthly Branch (Shichen)Animal SymbolLocal True Solar Time WindowElement & PolarityNotes on Boundaries
1Zi (子)Rat23:00 – 00:59 (11:00 PM – 12:59 AM)Yang WaterStraddles midnight; 23:00–23:59 differs between the 23:00 day-switch and Early/Late Zi conventions
2Chou (丑)Ox01:00 – 02:59 (1:00 AM – 2:59 AM)Yin EarthEarly morning; 01:00 marks the Zi–Chou transition
3Yin (寅)Tiger03:00 – 04:59 (3:00 AM – 4:59 AM)Yang WoodPre-dawn hours
4Mao (卯)Rabbit05:00 – 06:59 (5:00 AM – 6:59 AM)Yin WoodSunrise window (06:00 equinox solar sunrise)
5Chen (辰)Dragon07:00 – 08:59 (7:00 AM – 8:59 AM)Yang EarthMorning hours
6Si (巳)Snake09:00 – 10:59 (9:00 AM – 10:59 AM)Yin FireLate morning
7Wu (午)Horse11:00 – 12:59 (11:00 AM – 12:59 PM)Yang FireSolar noon window (12:00 is local solar noon when the Sun crosses the meridian)
8Wei (未)Goat / Sheep13:00 – 14:59 (1:00 PM – 2:59 PM)Yin EarthEarly afternoon
9Shen (申)Monkey15:00 – 16:59 (3:00 PM – 4:59 PM)Yang MetalMid-to-late afternoon
10You (酉)Rooster17:00 – 18:59 (5:00 PM – 6:59 PM)Yin MetalSunset window
11Xu (戌)Dog19:00 – 20:59 (7:00 PM – 8:59 PM)Yang EarthDusk and evening
12Hai (亥)Pig21:00 – 22:59 (9:00 PM – 10:59 PM)Yin WaterLate evening; 23:00 marks the start of the Zi hour

Why Two Calculators Can Disagree on an 11:30 PM Birth: Whole Zi vs. Early/Late Zi

In pre-modern China, the Zi double-hour began at 23:00 (Zi Chu). When modern civil calendars fixed the date change at 00:00 midnight (Zi Zheng), two schools of practice emerged for births occurring between 23:00 and 23:59 local True Solar Time:2

FeatureConvention A: Whole Zi / 23:00 Day ChangeConvention B: Split Early/Late Zi / 00:00 Midnight Day Change
Xiaodao "Early/late Zi" Setting"No" (Default)"Yes" (Page helper note: non-specialists don't need to touch this; the default is fine)
When the Day Pillar ChangesAt 23:00 local True Solar TimeAt 00:00 midnight local True Solar Time
Day & Hour Pillars for a 23:00–23:59 BirthFrom 23:00 onward, the Day Pillar is the next day's pillar, and the Hour Stem is derived from the next day's Day StemCounts as Late Zi (Night Zi, 晚子时 / 夜子时): the Day Pillar remains the current day's pillar, while the Hour Stem borrows the next day's Day Stem (e.g., on a Jia day, Late Zi is Bing-Zi)
Day & Hour Pillars for a 00:00–00:59 BirthCasts the Day Pillar for the birth date (the new day), with the Zi Hour PillarCasts the Day Pillar for the birth date (the new day), and the Hour Pillar is Early Zi (早子时)

For example, if Day 1 is Jia-Zi and Day 2 is Yi-Chou, a birth at 23:30 local solar time on Day 1 receives the Yi-Chou Day Pillar (Yi Wood Day Master) and Bing-Zi Hour Pillar under Convention A, whereas under Convention B (Late Zi) it retains the Jia-Zi Day Pillar (Jia Wood Day Master) while borrowing the next day's Yi stem to form the Bing-Zi Hour Pillar. For a birth between 00:00 and 00:59, both conventions cast the Day Pillar for the birth date (the new day) with the Early Zi Hour Pillar.

General-purpose chat models that cast BaZi charts without asking or disclosing their Zi-hour rule often default silently to 00:00 civil midnight or 23:00 clock time without converting to True Solar Time first; we recommend checking any late-night birth with a calculator that displays both True Solar Time and the active Zi convention.

How to Check a Late-Night or Odd-Hour Birth on Xiaodao

  1. Check True Solar Time first: A clock birth at 11:20 PM (23:20) during summer Daylight Saving Time or in a city west of its time zone's meridian often converts to 10:15 PM (22:15, the Hai Hour) in local True Solar Time—meaning it does not fall in the Zi hour at all.
  2. Choose your "Early/late Zi" preference if needed: In Xiaodao's BaZi Calculator, "Early/late Zi" defaults to "No" (23:00 day switch). If you follow the split Zi tradition, switch "Early/late Zi" to "Yes".
  3. Use the boundary prompt: When a birth time lands close to a two-hour branch boundary or day boundary, the page pops up a choice so you can confirm which side of the boundary to cast.3

Frequently Asked Questions

No. Once local True Solar Time passes 00:00 midnight (00:00–00:59), both conventions cast the Day Pillar for the birth date (the new day), with the Zi (Early Zi) Hour Pillar. The difference applies only when local True Solar Time falls between 23:00 and 23:59.

Born Near 11 PM or an Odd-Hour Boundary? Check Your Pillars

Enter your birth date, local clock time, and birthplace in Xiaodao's free BaZi Calculator to check local True Solar Time, toggle "Early/late Zi" if needed, and confirm boundary choices. Visitors can preview the four natal pillars and header details without signing in; signing up and saving a profile unlocks the Luck Pillars, annual, and monthly Timeline. First-time registration grants 200 Dao Points immediately upon sign-up.

Cast a Bazi chartSample report

Sources

  1. 1

    Hong Kong Observatory, Heavenly Stems and Earthly Branches. The twelve Earthly Branches and two-hour shichen periods.

  2. 2

    Wan Minying, San Ming Tong Hui, volume 2, “论四时节气,” “论遁月时,” and “论年月日时.” Classical branch hours and Hour Stem derivation.

  3. 3

    Xiaodao, public FAQ (https://xiaodaox.com/en/guide/faq), checked October 22, 2026.